Ferdinand a



(No Model.)

I. A. WESSEL. AUTOMATIC STARTING SWITCH FOR ELECTRIC MOTORS. No. 453,320. Patented June 2,1891.

IN\/E/\/ 7-0/1 Fardz'rzwwl J7 Wessl UNITED STATES PATENT OFFICE.

FERDINAND A. VESSEL, OF BROOKLYN, ASSIGNOR TO THE EXCELSIOR ELECTRIC COMPANY, OF NE\V YORK, N. Y.

AUTOMATIC STARTING-SWITCH FOR ELECTRIC MOTORS.

SPECIFICATION forming part of Letters Patent No. 453,320, dated June 2, 1891. Application filed January 9, 1891. Serial No. 377,271. (No model.)

To all whom it may concern.-

Be it known thatI, FERDINAND A. WEssEL, a citizen of the United States, and a resident of Brooklyn,in the county of Kings and State of New York, have invented a certain new and useful Automatic Starting-Switch for Electric Motors, of which thefollowing is a specification.

My invention relates to starting-switches for electric motors, and specially motors fed from constant-potential wires.

The object of my invention is to prevent damage to the motor by means of a sudden flow of excessive current through the same.

\Vhen a motor-armaturerevolves at a slow rate of speed its counter electro-motive force is small, and hence it oifers very little resistance to the flow of current through it. As the speed rises, the counter electro-motive force,

gradually rises also, until, when the normal speed has been attained, there will be a normal flow of current through such armature. It is, moreover, well known that an increase of load will reduce the speed of the armature and in reducing its counter electro-motive force will give rise to the flow of an abnormally strong current therethrough. The effect of this abnormally strong current passing through the armature, when its speed is slow either at starting or from overloading or any other use, is the great liability to burn the armature before it attains the requisite speed. To prevent this destructive tendency it has been customary heretofore to provide an artificial resistance placed into the armature connection and gradually thrown or cut out as the speed rises by a switch-lever operated by hand.

7 My present invention is designed to remove the necessity of manipulating the switch-lever by hand and which heretofore existed.

My invention consists in the special combinations of apparatnshereinafter described, and specified in the claims.

In the accompanyingdrawing I have shown in diagrammatic representation what I con sider the best means of carrying my invention into effect.

The figure is a diagrammatic representation of an organization embodying the invention.

Referring to the drawing, it will be seen that the motor M is connected with the mains on m.

F is the usual field-magnet, and A the usual rotary armature included in the connection 8, which leads from one main through the brushes B B and the said armature, and also through the artificial resistance r and switch lever or arm Z, together constituting the starting or rheostatic switch, and thence to the other main m.

Under the present invention the switch-lever Z is fulcrumed in proximity to the poles P of the field-magnet, preferably, as shown in the drawings, by hinging the same on a block b, of insulating material, attached to the pole-pieces. The resistance 0", over which the said lever travels, is also mounted on the pole-pieces and insulated therefrom at 2'. The switch-lever is provided with an armature or keeper 7, secured thereto. A spring S connects the lever Zwith a fixed bracket 1), which may, as shown, be attached to one of the polepieces. This spring serves to hold the lever Z in its uppermost position, in which all the coils of the resistance r are introduced when no current is passing. In order that the attraction of the keeper R and descent of the lever Zwhen the current is passing and the field magnets are energized may be gradual and sufficiently slow to cut out the coils of the resistance r in proportion to the speed acquired by the rotary armature, I interpose a retarding device between the lever and the bracket 1), which is so adjusted as to insure the lapse of a predetermined space of time before the lever is completely drawn down and the entire resistance cut out. In the present instance I have shown this retarding device as consisting of a dash-pot d, of any suitable construction, whose arrangement and mode of operation are sufficiently well known and need no further description here. It is, however, manifest that any other suitable retarding device may be employed in lieu of the daslrpot d. For example, in some instances the spring s" itself might be so adj usted in tension as to serve the additional function of a retarding device. The said spring would, moreover, actas a regulating device responsive to the strength of current, and hence of the speed of the armature, whereby the amount of the interposed resist ance would be automaticallyadjusted to such speed and would vary with variations of speed both at starting and at stopping and under changes of load. I may, therefore, in some instances omit the dash-pot and cause the spring .9 to perform the double function above set forth.

The operation of the apparatus thus described will be plain from the above description and is as follows: hen it is desired to start the motor, the switch-lever s is turned so as to close the circuit and to energize the field-magnets F. The armature slowly begins to revolve. At this stage of the operation, when, by reason of its small speed, the armature produces but a slight counter-current to the high-potential current passing through the mains, the passage of this full current and the consequent injury to the armature is prevented by the resistance r, all of whose coils are included in the shunt-circuit s at startin The field-magnet being energized begins to attract the armature or keeper 7*, drawing down the lever Z to cut out the resistance. This movement is gradual and so controlled by the dash-pot cl that a predetermined time elapses, sufficient for the rotary armature A to have acquired the requisite speed before the lever Z is completely drawn down and all the resistance-coils are cut out.

When no dash-pot is used, the spring 8 is adjusted so that its resiliency will balance the attraction due to the strength of the passing current when the lever Z has described a certain path and cutout a certain number of coils of the resistance. The regulating action will hence'be automatic and conform to the speed of the armature.

Vhile I consider the construction shown as the preferable form for carrying my invention into effect, it is evident that the same may be greatly varied and modified without departing from my said invention. I do not desire, therefore, to be limited to the details herein shown, but

lVhat I claim, and desire to secure by Letters Patent, is

1. The combinatiomwith an electric motor fed from constant-potential mains, of a rheostatic switch the whole or greater part of whose resistance is included in the armaturecircuit when the motor is at rest and running at slow speed, said resistance being independent of the field-magnet and in a separate branch with the armature of the motor, an armature or keeper placed within the influence of the field-magnet and connected to the rheostatic switch, and a retarding device, substantially as and for the purpose described.

2. The combination, with an electric motor fed from constant-potential mains, of a rheostatic switch the whole or a greater part of whose resistance is included in the armaturecircuit when the machine is at rest or running at a slow speed, said resistance being independent of the field-magnet and in a separate branch around the same, a switch-lever provided with a keeper placed within the influence of the field-magnet, and a spring tending to hold the switch-lever away from the field-magnet, substantially as and for the purpose described.

3. The combination, with an electric motor fed from constant-potential mains, of a rheostatic switch the resistance of which is interposed in the circuit of the armature when the machine is at rest, said resistance being in a branch independent of the field-magnet coils, a switch-lever provided with a keeper subjected to the influence of the field-magnet, a spring for holding the switch-lever away from the field-magnet, and a retarding device for controlling the movement of the switchlever as it is drawn down to cut out resistance when the machine is thrown into action.

Signed at New York, in the county of New York and State of New York, this 27th day of December, A. D. 1890.

FERDINAND A. \VESSEL.

Witnesses:

WM H. OAPEL, T. F. COUREY. 

